ubtless utilized in neighboring constructions, since it is hardly
to be supposed that it was carried away to any considerable distance.

The purpose of this hollow mound, which is a fair type of many similar
structures found in this region, is not clear. Mr. Frank Hamilton
Cushing, while director of the Hemenway southwestern archeological
expedition, found a number of these structures and excavated some of
them. From remains thus found he concluded that they were sun-temples,
as he termed them, and that they were covered with a roof made of coiled
strands of grass, after a manner analogous to that in which pueblo
baskets are made. A somewhat similar class of structures was found by
the writer on the upper Rio Verde, but these were probably thrashing
floors. Possibly the structure under discussion was for a similar
purpose, yet its depth in proportion to its size was almost too great
for such use. The question must be left for determination if possible by
excavation.

In the southern central part of the map is shown another excavation,
covering a larger area than any of the others, of very irregular outline
and from 3 to 4 feet deep. It is apparently older than the others and
probably furnished the material for the house structures northeast and
southwest of it. Bordering the depression on the south there are some
low mounds, almost obliterated, which probably were the sites of other
house structures.

Scattered about the area shown on the map there are several small
depressions, usually more regular in outline than those described. The
best example is situated near the northeastern corner of the area. It is
situated in the point of a low promontory, is about 3 feet deep, almost
regularly oval in outline, and measures about 50 by 100 feet. A similar
depression less than 2 feet deep occurs near the northwest corner of the
area, and immediately south of the last there is another, more irregular
in outline, and nearly 3 feet deep. There are also some small
depressions in the immediate vicinity of the Casa Grande ruin and of the
mounds north of it.

With a single exception none of these depressions are so situated that
they could be used as reservoirs for the storage of water collected from
the surface, and the catchment area of the depressions is so small and
the rate of evaporation in this area so great that their use as
reservoirs is out of the question. It is probable that all of the
smaller depressions represent sim